Commit 164d88ab authored by Alexander Aring's avatar Alexander Aring Committed by David Teigland
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fs: dlm: requestqueue busy wait to event based wait 



This patch changes the requestqueue busy waiting algorithm to use
atomic counter values and wait_event() to wait until the requestqueue is
empty. It will slightly reduce the number of holding ls_requestqueue_mutex
mutex.

Signed-off-by: default avatarAlexander Aring <aahringo@redhat.com>
Signed-off-by: default avatarDavid Teigland <teigland@redhat.com>
parent 92732376

fs/dlm/dlm_internal.h

+2 −0
Original line number Diff line number Diff line
@@ -626,6 +626,8 @@ struct dlm_ls { 
	struct rw_semaphore	ls_in_recovery;	/* block local requests */

	struct rw_semaphore	ls_recv_active;	/* block dlm_recv */

	struct list_head	ls_requestqueue;/* queue remote requests */

	atomic_t		ls_requestqueue_cnt;

	wait_queue_head_t	ls_requestqueue_wait;

	struct mutex		ls_requestqueue_mutex;

	struct dlm_rcom		*ls_recover_buf;

	int			ls_recover_nodeid; /* for debugging */

fs/dlm/lockspace.c

+2 −0
Original line number Diff line number Diff line
@@ -564,6 +564,8 @@ static int new_lockspace(const char *name, const char *cluster, 
	init_rwsem(&ls->ls_in_recovery);

	init_rwsem(&ls->ls_recv_active);

	INIT_LIST_HEAD(&ls->ls_requestqueue);

	atomic_set(&ls->ls_requestqueue_cnt, 0);

	init_waitqueue_head(&ls->ls_requestqueue_wait);

	mutex_init(&ls->ls_requestqueue_mutex);

	mutex_init(&ls->ls_clear_proc_locks);

fs/dlm/requestqueue.c

+7 −8
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_message *ms) 
	e->nodeid = nodeid;

	memcpy(&e->request, ms, ms->m_header.h_length);



	atomic_inc(&ls->ls_requestqueue_cnt);

	mutex_lock(&ls->ls_requestqueue_mutex);

	list_add_tail(&e->list, &ls->ls_requestqueue);

	mutex_unlock(&ls->ls_requestqueue_mutex);
@@ -89,6 +90,8 @@ int dlm_process_requestqueue(struct dlm_ls *ls) 


		mutex_lock(&ls->ls_requestqueue_mutex);

		list_del(&e->list);

		if (atomic_dec_and_test(&ls->ls_requestqueue_cnt))

			wake_up(&ls->ls_requestqueue_wait);

		kfree(e);



		if (dlm_locking_stopped(ls)) {
@@ -115,14 +118,8 @@ int dlm_process_requestqueue(struct dlm_ls *ls) 


void dlm_wait_requestqueue(struct dlm_ls *ls)

{

	for (;;) {

		mutex_lock(&ls->ls_requestqueue_mutex);

		if (list_empty(&ls->ls_requestqueue))

			break;

		mutex_unlock(&ls->ls_requestqueue_mutex);

		schedule();

	}

	mutex_unlock(&ls->ls_requestqueue_mutex);

	wait_event(ls->ls_requestqueue_wait,

		   atomic_read(&ls->ls_requestqueue_cnt) == 0);

}



static int purge_request(struct dlm_ls *ls, struct dlm_message *ms, int nodeid)
@@ -161,6 +158,8 @@ void dlm_purge_requestqueue(struct dlm_ls *ls) 


		if (purge_request(ls, ms, e->nodeid)) {

			list_del(&e->list);

			if (atomic_dec_and_test(&ls->ls_requestqueue_cnt))

				wake_up(&ls->ls_requestqueue_wait);

			kfree(e);

		}

	}